OM616 throttling question
I recently aquired a OM616 out of a 74 220D. The body was wasted from rust, which was fine since i was just after the engine and maybe trans for a conversion project i want to do this winter. I got the engine out and on my stand and after some tinkering i got it fired up and running, but i am confused as to what or how the throttling works on these engines. I am used to working on diesels but have never run across one with a butterfly throttle in the intake...and this engine appears to actually have 2 of them one right behind the other. With the engine running the linkage between the butterfly and the inj pump came off and the butterfly would still regulate the engines speed all be it it did not run as well at higher rpms without the inj pump also being accelerated...but just moving the inj pump lever did very little to speed it up, it just made it run rougher like it was to rich...which im sure is what it was doing. Normal diesels have full open air intakes and just throttle with the inj pumps fuel delivery. So....whats the story on these engines and the odd setup?
Next question is, what can one do to this early OM616 to get maybe 20 more hp...currently rated at just over 60 i am told, but for what i am wanting to use it in....1951 willys cj3a, i would like about 80 so it will handle the overdrive unit better while still having the low gearing for mountain trail running. Would love to turbo it, but am told they wont handle one due to lack of piston oil cooling nozzles. What do you fellas in the know think? Can the pump be tweeked up enough to get 20 more hp?
Thanks very much for any insight you can share.